Kovacs effect and fluctuation-dissipation relations in 1D kinetically constrained models

TL;DR

This paper investigates how changing constraints in 1D kinetically constrained models affects glass relaxation, revealing the Kovacs effect and surprising fluctuation-dissipation relation behaviors in out-of-equilibrium dynamics.

Contribution

It demonstrates that both symmetric and asymmetric models exhibit the Kovacs effect and satisfy fluctuation-dissipation relations, contrasting with previous quenching results.

Findings

Kovacs effect is present in both models, enhanced in asymmetric case.

Fluctuation-dissipation relations satisfy the FD theorem in both models.

Contrasts with quenching procedures where asymmetric models deviate from FD theorem.

Abstract

Strong and fragile glass relaxation behaviours are obtained simply changing the constraints of the kinetically constrained Ising chain from symmetric to purely asymmetric. We study the out-of-equilibrium dynamics of those two models focusing on the Kovacs effect and the fluctuation--dissipation relations. The Kovacs or memory effect, commonly observed in structural glasses, is present for both constraints but enhanced with the asymmetric ones. Most surprisingly, the related fluctuation-dissipation (FD) relations satisfy the FD theorem in both cases. This result strongly differs from the simple quenching procedure where the asymmetric model presents strong deviations from the FD theorem.